Aristotle's Reform of Paideia: Article by Evelyn Barker, arguing that the principal aim of Aristotle's Organon was to reform the contemporary paedagogical role of dialectic.
Earliest Uses of Symbols of Set Theory and Logic: Explains the early introduction of notations used in logic and set theory as we know it today. Includes reference links to key people in this area.
Logic: Entry in the Catholic Encyclopaedia (1917), dominated by a historical survey from Indian and Pre-Aristotelian philosophy to the Logic of John Stuart Mill.
On Dialectic: By St. Augustine. Latin original together with translation by J. Marchand.
Peter of Spain (Petrus Hispanus): Life and work of 13th century logician and author of the Tractatus; from the Stanford Encyclopedia by Joke Spruyt.
Scholastic Logic: Chapter Two of Joseph Perrier's "The Revival of Scholastic Philosophy in the Nineteenth Century" (1909).
Scholasticism: Online text by Joseph Rickaby (1908).
Square of Opposition: Article in the Stanford Encyclopaedia of Philosophy, by Terence Parsons.
Syllogistic logic online: This site contains an online program for studying Aristotle's syllogistic logic. The theory of Aristotle's ancient logic is also presented.